Steel that constitutes molds for press-molding steel materials by hot stamping or the like are required to have a high thermal conductivity. So long as a steel for mold has a high thermal conductivity, the mold can deprive the steel material of the heat at a high rate to heighten the hardenability. In addition, the mold can be efficiently cooled during the period from the completion of the working of one steel material to the introduction of the next steel material, and the working cycle time can hence be shortened to improve the production efficiency.
For example, Patent Document 1 discloses a tool steel which is an inexpensive steel having a low rare-element content and which, despite this, can be used for constituting molds having high resistance to softening and a high thermal conductivity. This tool steel contains, in terms of % by mass, from 0.15 to 0.55% C, from 0.01 to 0.5% Si, from 0.01 to 2.0% Mn, from 0.3 to 1.5% Cr, from 0.8 to 2.0% Mo, from 0.05 to 0.5% V+W, from 0.01 to 2.0% Cu, and from 0.01 to 2.0% Ni, with the balance being Fe and unavoidable impurities.
Patent Document 1: JP-A-2009-13465